Collection catheters are well known for collecting blood or other fluids from blood vessels of a patient, for example, for collecting blood from a coronary sinus or other coronary vein in a perfusion process. In addition to collecting blood in a perfusion process, blood may be collected from a coronary vein in an angiography procedure. Such procedures are used for assessing patency of coronary arteries. In such a procedure, a contrast medium is injected into a coronary artery for visualization of a suspected site of a coronary obstruction.
Contrast media may have significant health risks if permitted to flow systemically to the patient's organs. For example, renal dysfunction or failure may occur from such systemic delivery of a contrast media. Such failure is referred to as “contrast-induced nephropathy” or CIN. Accordingly, patients often undergo a contrast removal procedure to remove the contrast media from systemic delivery.
Blood collected in a contrast removal procedure may be processed to be re-admitted to the patient. However, it is more common for collected blood to be discarded. It is generally recognized that a limited amount (e.g., 150 milliliters to 200 milliliters) of blood may be safely removed from a patient and discarded.
Blood collection techniques include methods and apparatus for isolating blood flow in a vessel. This insures that primarily antegrade flow (i.e., the normal direction of blood flow in a vessel) is collected for a period of time for substantial collection of all contrast media or perfusate that is the object of collection.
Importantly, such isolation is employed to avoid collection of significant retrograde blood flow. Retrograde flow (in a direction opposite normal blood flow in a vessel) may occur, for example, where a catheter draws blood from a coronary sinus under suction. The suction may be such that blood in the right atrium flows retrograde and is drawn through the catheter. As a result, blood not laden with contrast media or perfusate is collected and possibly discarded. Since there are limits on how much blood may be discarded, it is desirable to minimize collecting and discarding blood not laden with contrast media or perfusate. Isolation or partial isolation is commonly achieved through use of balloon catheters. A balloon is inflated during periods of blood collection to seal against the wall of the blood vessel. Otherwise, the balloon is deflated to be spaced from the blood vessel wall.
In addition, individual anatomical differences may result in a coronary vein that empties into the coronary sinus, for example, proximal to the balloon or sealing member. Contrast or perfusate entering from such a vein may not be captured through a distal opening of the catheter.
Improvements to catheter systems and collection methods are needed, generally to, for example, collect contrast media or perfusate proximal to a sealing member, while minimizing the amount of retrograde flow collected. Further objectives of this disclosure may include systems and methods that additionally allow for selective and/or differential collection of contrast media or perfusate from various locals within a vessel and along a collection device.